Paper ID #23003

Development of a Virtual Reality Flight Simulator to Assist in the Design ofOriginal Aircraft

Dr. Dominic M. Halsmer P.E., Oral Roberts University

Dr. Dominic M. Halsmer is a Professor of Engineering and former Dean of the College of Science andEngineering at Oral Roberts University. He has been teaching science and engineering courses therefor 26 years, and is a registered Professional Engineer in the State of Oklahoma. He received BS andMS Degrees in Aeronautical and Astronautical Engineering from Purdue University in 1985 and 1986,and a PhD in Mechanical Engineering from UCLA in 1992. He received an MA Degree in BiblicalLiterature from Oral Roberts University in 2013. His current research interests involve the use if virtualreality for engineering education, the integration of faith and learning, contributions from the field ofengineering to the current science/theology discussion, reverse engineering of complex natural systems,and the preparation of scientists and engineers for missions work within technical communities.

Mr. John A. Voth, Oral Roberts University

John Voth is a current senior mechanical engineering student at Oral Roberts University. He will pursuehis PhD from the University of Minnesota after graduation.

Mr. Connor A. McCain, Oral Roberts University

Connor McCain is an undergraduate engineering student at Oral Roberts University.

Mr. Jordan David Reutter, Oral Roberts University

Jordan is Mechanical Engineering Student at Oral Roberts University Graduating in May 2018. He’sbeen involved with many projects such as The Hyperloop Competition and is currently interning with TheBoeing Company. He was primarily involved with the design and manufacturing of Team Soar’s flightsimulator serving as a design engineer.

Nathaniel Shay FraileyMatthew SamuelsonMr. David Ahrens, Oral Roberts University

c©American Society for Engineering Education, 2018

Development of a Virtual Reality Flight Simulator

to Assist in the Design of Original Aircraft (Work in Progress)

ABSTRACT

The undergraduate engineering curriculum is extremely challenging, largely due to the

complexity of the processes and concepts it introduces. One good way to handle this complexity

and assist students in learning about the development of engineered products is by providing

enhanced visualization of the processes and concepts involved. This has been recognized

recently by several researchers who are attempting to harness state-of-the-art virtual reality

experiences to improve the quality of engineering education. This has prompted one group to

write, "Virtual reality has grown up. Once an exotic field of computer sciences, it is now an

important topic for the engineers of tomorrow."1

The engineering research and development of a virtual reality flight simulator seems like a good

way to engage undergraduate engineering students with the up-and-coming field of virtual

reality. A multidisciplinary team of students at our university are pursuing this as their senior

capstone design project. The completed system will serve as an addition to the engineering labs

and assist future students with their design of original aircraft. With the help of a HTC Vive

virtual reality headset, the system will simulate the cockpit environment and faithfully respond to

pilot control inputs. The pilot will be strapped into a seat to be rigidly mounted atop a Stewart

platform, which will roughly simulate the dynamics of a student’s custom aircraft design.

This virtual reality aircraft motion simulator will be developed through extensive engineering

analysis that enhances engineering education both for those developing the simulator and for

those who will use it in design. First, the geometry of the simulator will be mathematically

analyzed and defined by the students, which will enable optimal geometries to be solved for to

maximize certain ranges of motion. Then, the dynamics of the system will be simulated using

MATLAB's Simulink technology to confirm the simulator's theoretical dynamic performance,

verify the ranges of motion from the students' mathematical analysis, and provide the necessary

specifications for the motors. Furthermore, structural analysis with SolidWorks will be used to

calculate the factor of safety of the system, which will help properly size the rotary actuators.

This engineering analysis of the simulator will function to increase exposure to principles of

aircraft design to both technical and non-technical students alike. The simulator is tailor-made to

accompany our university's Aircraft Design course. By pairing the our simulator with the course

engineering students will be able to learn about aircraft design, create their custom airplane using

X-Plane 11’s plane maker software, and then experience flying it on our simulator. This

immediate, immersive feedback enriches the students' knowledge of aircraft design and increases

interest in the topic. Additionally, the portable design of the simulator enables the system to

serve as an exciting advertisement to pre-college students considering the world of STEM

studies.

RECENT WORK IN VIRTUAL REALITY AND FLIGHT SIMULATION

As virtual reality is becoming more accepted and found to be useful in industry, these

experiences are finding their way into the engineering classroom and laboratory. The 2017 ASEE

Annual conference saw two papers that described how virtual reality is being used in

construction engineering education. Hao et al explain how virtual reality is used to recreate the

complex structures and construction techniques of dougong, a unique characteristic of ancient

Chinese architecture, in an environment where users can interact with objects with a high degree

of realism. Students benefit by examining structures and techniques via static images, dynamics

videos and VR interactivity, which are all compiled and integrated into a knowledge-based

system known as the Intelligent Dougong System with Virtual Reality (IDSVR). Multiple

presentation methods of dougong construction were then conducted with Autodesk 3DS MAX

and virtual simulations using the Oculus Rift.2 In another paper from last year, virtual reality was

used to illuminate ancient engineering and construction methods used in the Jinshanling region

of the Great Wall of China. A VR simulation using the Oculus Rift and an Xbox controller,

allows students to examine the construction process in a virtual environment. Thus, this study is

expected to permit students to immerse themselves in the virtual erection process of ancient

structures in a classroom setting.3

Flight simulators are also being used to enhance engineering education. To increase student

engagement and provide an enriched learning environment, Memon et al integrated a flight

simulator into a Flight Vehicle Performance course. Class performance revealed that students

enhanced their knowledge of aircraft stability and control through flight simulator experience.

Reflections from the students showed that they benefited greatly from the intuitive theoretical

learning through the use of flight simulator.4 Indeed, an earlier paper described the benefits of

integrating experience-based system simulation modules into a series of vehicle dynamics

courses, including a flight dynamics course. The authors claim that, “The benefits of imitating a

real process by way of simulation cannot be understated. The educational value of simulations

does not necessarily lie in the program itself, but rather, in the overall experience of the

simulation.”5 It is hoped that the following project can integrate a hands-on virtual reality

experience with a high-fidelity flight simulator to enhance student understanding of various

aspects of aircraft design and their impact on aircraft dynamics, stability, and performance.

To embark upon the complex endeavor of this project, an understanding of flight simulation first

had to be obtained by the team. At the beginning of this journey, the team had discovered that the

Stewart Platform was commonly used in the flight simulation field due to its ability to operate in

all six degrees of freedom. Immediately, they began to seek after highly academic sources on

Stewart Platform motion and the mathematics that governed it. They viewed sources such as

Detecting Singularities of Stewart Platforms6 and Stewart Platform with Fixed Rotary Actuators:

A Low-Cost Design Study.7 These sources gave great initial understanding of the motion that a

Stewart Platform can provide and the geometric constraints that must be upheld within its

construction; however, they primarily provided information that was beyond the scope of this

project and the mathematical understanding of the undergraduates students on the team. To gain

a simpler comprehensive grasp of the topic, the team began searching online forums for

assistance. This was highly beneficial to the project. The team discovered that there are many

projects that have some similarity to their own. Through forum sites such as XSimulator8 and

Motionsim,9 the team was able to observe not only successful Stewart Platform designs, but also

failures that had occurred in the making of those designs. Although these sites are nonacademic,

they provided very valuable information pertaining to the structural geometry and electrical

interfaces of the system. While on these sites, the team mainly observed builds by users

SilentChill and GA-Dawg from XSimulator and Motionsim respectively.

INTRODUCTION

A team of six engineering students, under the direction of two faculty members from Oral

Roberts University (ORU), is researching a new, innovative approach to deepen undergraduate

students’ practical understanding of aircraft design. These undergraduate seniors are developing,

fabricating, and fine-tuning an aircraft flight simulator, which, along with the help of VR

technology, will realistically produce the motion effects of flight. This simulator will allow

undergraduate engineering students taking an aircraft design course to accelerate the iterative

aircraft design process. Also, students will be able to experience a higher degree of project

completion, flying their custom virtual aircraft by taking the flight controls in their own hands.

In the Aircraft Design course at ORU, students learn how to design an experimental aircraft

using “correct” specifications according to theoretical values. This educational process will be

improved by providing further connection between actual flight handling and the supporting

aircraft design theory. This paper will demonstrate students’ attempt to bridge this gap by the use

of their VR aircraft motion simulator. By the end of the 2017-2018 academic year, students will

be able to accurately test their custom aircraft designs at intermediate and final stages, speeding

up the iterative aircraft design process. Also, students will have the capability to realistically

experience flight in their own custom designed aircraft, and further solidify their understanding

as to why their aircraft flies the way it does.

The scope of this project, however, reaches beyond just enhancing educational opportunities for

engineering students. Several passive flights will be programmed for the general public’s

immersion, exposing prospective and nontechnical students to the world of aircraft design.

Additionally, the intentional portability of this simulator opens the doors for this simulator to be

presented in multiple unique locations. As a whole, this project functions as a powerful tool of

engineering education, providing an immersive learning experience to many, regardless of the

individual’s prior level of knowledge.

DESIGN GOALS

The project has three specific goals that the team aims to complete by the end of the Spring 2018

semester. First and foremost, the team is building a Stewart platform to simulate flight with six

degrees of freedom and virtual reality equipment. Therefore, the platform will have to

realistically move with the chosen software so as to allow for the user to feel like they are

experiencing the motion of the airplane. The chosen software also needs to connect with virtual

reality so as to further immerse the person in the flight experience. Next, the goal of the project is

to partner with the Aircraft Design course taught by Dr. Halsmer. In doing so, the chosen

software will allow for the option of customizability, so that students can create/model their own

original aircraft and see how their designs produce unique flight dynamics. The student can then

sit inside their virtual plane in the simulator and experience what it would be like to pilot their

aircraft. This will allow for students to get a first-hand experience of how certain design

parameters truly affect the overall flight characteristics of aircraft.

In addition to these design goals, the last major goal of the project is to house the Stewart

platform within ORU’s virtual reality lab in the Global Learning Center. In addition to educating

engineering students, the simulator will also be used as a promotional tool, both for the

university and the engineering department, and allow it to be a resource for what other needs the

university might have for a Stewart platform. With this in mind, a few more practical design

goals are being pursued. First, the simulator must be safe enough for people of all ages and sizes

to ride in. Also, the platform must carry a professional look so that the university can showcase it

and people will feel confident to ride in it. In addition to all this, since most of those riding in the

simulator will not have experience in controlling the simulator, the software chosen must allow

for passive flights so that the user doesn’t have to understand the mechanics of flying but instead

can be led through a flight without their having to do much. These secondary goals will serve to

increase access to the experiences of flight, and aircraft design (and their relationship to STEM)

to a wide swath of the general public.

CAD: DIGITAL CONSTRUCTION

Due to the complex nature of the flight simulator’s Stewart platform geometry, the team decided

upon the use of Computer-Aided Design (CAD) to digitally construct the system. Because of its

accessibility and wide range of capabilities, SolidWorks® was chosen as the CAD design

software best suited for the teams needs. Seeing as the team’s design of the Stewart platform is a

quite intricate system of rotary actuated arms, many preliminary design iterations were

performed to gain an understanding of the range of motion that the simulator will undergo within

its movement, and the geometry that dictates its structure. These initial iterations were primarily

drafted around other flight simulator models. Once a general understanding of the platform

geometry and mechanics had been obtained through CAD modeling, the team turned its attention

to designing their own custom simulator.

The designing process began on paper, as many do. Geometric relationships pertaining to the

platform had to be determined before a unique system could be developed within the

SolidWorks® software. Considering the complexity of the complete structure, simplifications

and constraints were required so that the geometry of the system could be established. This was

accomplished by observing an isolated pair of the dual actuation arm subsystem in a planar

configuration and having motion confined to vertical heave. By defining the arbitrary constants

of total heave displacement, the expected seat height, and the theoretical center of gravity of a

seated man, a complete set of geometric relationships was then obtained. These calculations

resulted in a one-to-five length ratio for the lower and upper actuator arm pair, or, more

precisely, a 5.5 inch lower actuating arm and 27.5 inch upper actuating arm. Pairs of this

configuration were then aligned along each side of an equilateral triangle, such that there are six

pairs total. A visual of the isolated subsystem can be observed below in Figure 1.

Figure 1: Dual Actuating Arms Isolated in Heave (observing maximum and minimum position)

After using graphical and mathematical analyses to develop the dimensional basis of the

structure, components and assemblies were drafted within SolidWorks. The rods and lever arms

were first designed, and additional assemblies, such as the lower and upper platforms, followed.

To test and visualize the system geometry, multiple prototype models were manufactured

through 3D printing scaled down by a factor of ten. These models were developed to provide a

functional test and proof of concept to the team’s design. The scaled prototype models have

behaved as expected and have proven the aforementioned analysis as operational.

Once the final system geometry was established and tested, the geometric framework drafted in

SolidWorks was converted into actual industrial components that could be purchased. These

parts were designed and chosen alongside a selection of vendors taking into account both cost

and availability. The parts were modeled to the exact specifications of the vendor or in some

cases, the vendor provided a premade, dimensionally accurate CAD model available for

download. The system was organized into a variety of assemblies and sub-assemblies. All

necessary drill holes were also added to the system components, and a few larger bolts were also

added to increase the factor of safety. By using mates to fix the lever arms of the Stewart

Platform in key positions, the team is also able to use the model to prove the system geometry

that was mathematically established as well as predict and design around any geometric

collisions. Several simulation exercises were run to ensure structural stability in key locations.

The accurate model also allowed us to generate weight estimates for the system. With the model

complete, a full bill of materials was developed, vendors were identified, and materials were

purchased. Drawings and blueprints were drafted and printed to ensure accurate manufacturing

of each component. Developing a complete and accurate model of our system in SolidWorks is

an important part of the teams educational vision as it shows students the power of CAD design

software and gives them the opportunity to compare a virtual rendering with manufactured

reality.

ENGINEERING DESIGN

Early on in the design of the platform, it was decided that the best positioning of the connecting

rods to the upper platform would be to have them at the center of gravity. This would

theoretically ensure that the center of gravity would not be changing and all movement could be

based around a fixed point. To solve this, a study done Dr. John J. Swearingen was used called

Determination of Center of Gravity of Man.10

The following analysis, illustrated in Figure 2,

comes from this study.

Figure 2: The Center of Gravity of a Seated Man

From page 20: Trunk 115°, knees 145°, hands on lap.

From the figure above:

Thus, the vertical positioning for the location of the connection rods was set 11 inches above the

bottom portion of the chair so as to be closer to the center of gravity. Likewise, the chair was set

5.24 in back from the center of the connection rods to try to account for the offset position of the

center of gravity.

A unique complication within the design portion was the stress analysis of the members of the

system. With such a complicated inverse dynamics problem to solve for the individual torques

and forces being experienced, the team was running out of time for solving what needed to be

done so that they could order the motors, and other parts. So the team needed to find a simpler

way to estimate the stresses the individual components would experience so as to quicken the

process. The solution was to create a “worst case” nearly impossible scenario. Since the

maximum weight of the top of the platform will be 300 lbs, stress estimations were made by

applying the entire load to single members. Due to the setup of the platform, this scenario should

never occur, but if it can be proven that the design can hold up well under this case, then there

should be no chance of failure at any point during use. A factor of safety of 2 was implemented

for the analysis. Using these parameters, stress analysis has been conducted on the upper

connecting rods and bolts that connect to the Heim joints and are as follows.

Therefore, if the outer diameter of the connecting rods is greater than 1.093 in, there should be

no chance of failure due to buckling.11

The electrical design of the system was primarily structured after a Systems Engineering and

Computing professor whose alias is SixDegreesOfFlight on the reputable XSimulator forum. His

design was a compilation of previous designers on the website. The design comprises one

Figure 3. S-N Diagram

primary module which is repeated three times. This module consists of one Sabertooth 2x60 amp

drive, one Arduino Uno, two 24V 30A AC/DC Switching Power Supply Units (PSUs), two 12V

Lead-Acid Batteries to capture regenerative current from the Sabertooths, two 100A stud diodes

to protect the PSUs, one 60A resettable fuse, two 12V car relays, two 10k Ohm 10-turn

potentiometers for positional feedback, two 0.1uF noise-filtering capacitors placed on the

Arduino, and 24V DC permanent magnet motors which are each a part of a customized linear

actuator.

Figure 4: Foundational Electrical Module Design by SixDegreesOfFlight

There are several differences in our team’s design. First, we will not be using customized linear

actuators, but will instead be using solely the 24V DC permanent magnet motors with worm-

gearboxes attached. Secondly, the team will substitute each of the modules’ Arduino Unos for

one Arduino Mega microcontroller. This is done for both cost reasons and a compiled design of

the Arduino IDE program. Additionally, the team will have no need for the 10-turn

potentiometers but will instead use single turn potentiometers. This is also for simplicity and cost

reasons. Another variance in the designs which doesn’t provide much discrepancy regards the

input power. Because SixDegreesOfFlight is based in Australia, the design is powered using

standard Australian 240V AC power outlets, with a maximum current of 10 Amps. However, our

design is based in the USA, and will be using 120V AC power outlets with a maximum current

of 15 Amps for their system. Shown in Figure 5 is a block diagram of the current but evolving

state of the design.

Figure 5: Master Electrical Block Diagram

FABRICATION

The fabrication of the system is being performed fully in-house at our university. Each

component is first fabricated according to its dimensions and the specifications of its SolidWorks

drawing. This includes all cuts and holes or any other modifications. Once each component has

been prepped for assembly, the team will move into the assembly phase. By following a

directional assembly procedure, each part will be fastened together using bolts and mending

plates for aluminum parts, and welding for steel. The system will be split into three major

subassemblies: the upper platform, the rods, and the base. Once these sub-assemblies have been

assembled, they will be combined into the final system. Figure 6 is a current SolidWorks

rendering of the system, and Figure 7 is a photograph that shows the current state of assembly.

The system is on schedule to be fully functional by the end of the Spring 2018 semester.

Figure 6: SolidWorks Model of the Stewart Platform for the Custom VR Flight Simulator

Figure 7: Photograph Showing the Current Status of Stewart Platform Fabrication

EDUCATIONAL BENEFIT

To enrich the feedback within the aircraft design process, the design team will streamline a

process within pre-existing aircraft design software, X-Plane 11, so that students may easily

create their own custom aircraft based on an assortment of parameters that they select. These

parameters include: engine power, power loading, maximum coefficient of lift, aspect ratio, wing

taper ratio, stall speed, and much more through the inputting the necessary dimensions for each

part of the aircraft. Using Dan Raymer’s Simplified Aircraft Design for Homebuilders.12

and

Aircraft Design: A Conceptual Approach,13

also by Raymer, the Aircraft Design students will

select or define the necessary components to input into X-Plane 11’s “Plane Maker” software.

For each detail of the aircraft, the students will be able to draft or alter their aircraft inside the

program. Then, using the VR aircraft motion simulator that our team designed and built, students

will be able to experience flying their custom aircraft in an immersive, highly accurate manner.

Along with the Aircraft Design course, the motion simulator will be used to explain basic

aerodynamic properties in a course, called Introduction to Engineering, for freshman engineering

students. They will learn about concepts such as lift, drag, and the relationships formed by

altering the design of an aircraft by virtually flying multiple aircraft. The program will have

several aircraft with severe design conditions to enhance or hinder the performance of certain

characteristics to provide a clear visual representation. For example, the students would be able

to fly a traditional design as well as a design with an extremely exaggerated wingspan. Because

lift depends on the area of the wing, the students will notice the second aircraft takes off at a

much slower speed than the traditional design. Other example aircraft would have exaggerated

fuselage diameters to explain drag, or even altered airfoil shapes to show the different factors

within airfoil design. The students would first receive a lecture to discuss the properties being

exhibited, and then allowed to schedule time to operate the motion simulator.

In addition to these technical applications of the motion simulator, several passive flights will be

programmed into the system, allowing prospective or non-technical students to experience

realistic aircraft flight. Passive flights allow anyone to experience the feeling of flying the

uploaded aircraft without the need to learn any of the control aspects. Such ventures are pre-

specified by the software and include takeoff, a short flight around the airport, and landing. This

additional application of the simulator increases interest, experience, and enthusiasm in

aerospace design to a wide audience, presenting STEM studies in an exciting light and providing

the university with an excellent recruitment tool. Not only will the current engineering students

benefit from the motion simulator, but the university as a whole will be able to use the project as

a representation of the scholastic excellence of the university. With the motion simulator located

inside the Global Learning Center at ORU, school field trips, university assessments, and

prospective student visits will all be able to watch and operate the educational tool being

designed by ORU engineering students.

FLIGHT SIMULATOR ASSESSMENT

In order to provide a complete assessment for the project, the design team will execute each of

the design goals as part of their senior design project. As previously specified, for a successful

project, they will develop a Stewart platform with six degrees of freedom and virtual reality

compatibility, clear applications for the Aircraft Design coursework, and permanent residence in

the virtual reality lab at the Global Learning Center. The latter goal separates into three specific

categories: the simulator must be safe for all ages and sizes as specified, model a professional

appearance, and provide the opportunity for passive flight. If all of these goals have been met,

the project can be considered successful.

EDUCATIONAL ASSESSMENT PLAN

The ORU Aircraft Design course will be taught again to upper division undergraduate

engineering students in the 2018-2019 academic year. It is planned to utilize the custom VR

flight simulator to assist in motivating students during their aircraft design projects, and provide

additional insight into the aircraft design process. After students get an idea of the size of their

original aircraft, by estimating the power loading, wing loading, drag, lift-to-drag ratio and fuel

fraction, the take-off weight can be approximated. This is followed by engine sizing and

selection, wing geometry and placement, airfoil selection and tail geometry and sizing. Before

too long, the student will be able to “rough out” their original aircraft in X-Plane by specifying

all the necessary design parameters. This will give students the opportunity to take their first

draft aircraft on its virtual maiden voyage. (Of course, it will be helpful if they have some kind of

flight performance baseline with which to compare. For this reason, every student will be

required to spend a certain amount of virtual flight time in a standard trainer, such as a Cessna

150, prior to trying out their designs.) Virtual flight performance can then be compared to

predicted/desired performance and appropriate design modifications made. Multiple design

iterations are expected until students are satisfied with performance and the resulting designs.

Since this will be the first time to use the custom VR flight simulator in the Aircraft Design

course, student learning in this course will be compared to student learning previously taught

Aircraft Design courses. Exam and final project performance will be compared on an inter-

course absolute scale to see if the understanding of aircraft design has improved since the

introduction of the simulator. Survey data will also be collected from students in an effort to

assess motivation, enjoyment, learning, skill and confidence in aircraft design.

CONCLUSION

This paper has demonstrated the promise of using student-led innovation to improve the

educational experience of engineering students. From its inception, this project has been team-

focused and interdisciplinary, and it has provided a wonderful learning experience for the six

engineering students involved. They have had much experience in applying their theoretical

knowledge from class into the practicality of the build, gaining invaluable problem solving skills

along the way. But most excitingly, once this project is completed in a few weeks, the motion

simulator will benefit engineering and non-technical personnel alike for many years to come.

The students of this project cannot wait to conclude the project soon so that their efforts may

make engineering education more appealing and inviting. They are proud of their work and

excited that they have been making a positive contribution to their learning environment.

BIBLIOGRAPHY

1. P. Hafner, V. Hafner, J. Ovtcharova, “Teaching Methodology for Virtual Reality: A Practical

Course in Engineering Education,” Procedia Computer Science, Vol. 25, pp. 251-260, 2013.

2. S. Hao, A. H. Tan, F. Yang, F. H. Tan, and M. Parke, “Educational Application of Virtual

Reality in Graphical Simulation of the Construction Process of Chinese Dougong,” ASEE

Annual Conference, Columbus, Ohio, June 25-28, 2017.

3. J. R. Yang, F. H. Tan, A. H. Tan, and M. Parke, “Classroom Education Using Animation and

Virtual Reality of the Great Wall of China in Jinshanling,” ASEE Annual Conference,

Columbus, Ohio, June 25-28, 2017.

4. M. O. Memon, D. Erdahl, and S. R. Qureshi, “Empowering Students to Teach Flight

Dynamics and Flight Simulation Enhanced Learning through Applied Modeling,” ASEE Annual

Conference, Columbus, Ohio, June 25-28, 2017.

5. K. Lewis, K. Hulme, E. Kasprzak, D. Moore-Russo, P. Singla, and K. English, “Teaching

Automobile, Flight And System Dynamics Using Innovative Motion Simulation Experiments,”

ASEE Annual Conference, Louisville, KY, June 20-23, 2010.

6. Charters, T, et al. “Detecting Singularities of Stewart Platforms.” Mathematics-in-Industry

Case Studies Journal, vol. 1, 2009, pp. 66–80.

7. Szufnarowski, Filip. “Stewart Platform with Fixed Rotary Actuators: A Low-Cost Design

Study.” Semantic Scholar, Allen Institute for Artificial Intelligence, 2012,

www.semanticscholar.org/paper/Stewart-platform-with-fixed-rotary-actuators-%3A-a-

Szufnarowski/95d841ba42f8917a4311e8d3eeb49731f9e90353.

8. Dustin Arrell, “Motion Simulator DIY Community,” XSimulator Motion Simulator,

www.xsimulator.net/.

9. “Motionsim Free Forum.” Motionsim, ProBoards, Inc., motionsim.freeforums.net/.

10. Swearingen, John J., “Determination of Center of Gravity of Man.” Federal Aviation Agency,

Aug. 1962.

11. Hibbeler, R. C., Mechanics of Materials. 8th

Ed., Pearson Prentice Hall, 2011.

12. Raymer, Daniel P., Dan Raymer's Simplified Aircraft Design for Homebuilders. Los Angeles,

CA: Design Dimension, 2003.

13. Raymer, Daniel P., Aircraft Design: A Conceptual Approach, 5th

Ed., American Institute of

Aeronautics and Astronautics, Inc., Reston, VA, 2012.